Channel carbon black process employing oil enrichment



A nl 25, 1961 J. Y. ROGERS, JR.. ETAL 2,981,504

CHANNEL CARBON BLACK PROCESS EMPLOYING GIL ENRICHMENT Filed Oct. 10, 1957 INVENTO JOE Y. ROGERS,

JOHN M. BROWN BY OTTO E. SPECHT m m wyvywz.

AT TOR N EYS United States Patent CHANNEL CARBON BLACK PROCESS EMPLOY- lNG OIL ENRICHMENT Joe Y. Rogers, Jr., John M. Brown, and Otto E. Specht, Pampa, Tex., assignors to Cabot Corporation, Boston, Mass, a corporation of Delaware Filed Oct. 10, 1957, Ser. No. 689,330

3 Claims. (Cl. 23209.8)

tofore serious difficulty has been encountered particularly 5 in the production of high color carbon blacks which have been produced only by means of air dilution of the combustible mixture. Moreover, it has been found that smoke loss becomes excessive above ratios of about 1 gallon distillate to 1250 cubic feet of natural gas. Recovery of smoke has been found impractical due to extremely high flue product volume.

Before the advent of oil enrichment, air dilution created no operational difliculties but with the use of oil air causes coking at the burner tips which results first in flame forking and ultimately blocking of the burner tips.

When it is desired to produce color blacks, air diluent must be added to the gas. Air oxidation of oil occurs above ratios of approximately 1 gallon distillate oil to 3750 cubic feet of diluted gas depending on the grade of black and distillate used.

This difficult problem has been solved in accordance with our invention by the introduction of an antioxidant into the combustion zone of an oil-gas-air mixture burning under conditions of incomplete combustion beneath a channel iron surface.

The features and characteristics of our invention will be best understood and appreciated from the following description of a typical manner in which it has been successfully carried out as illustrated in the accompanying drawing showing a typical channel hot house and equipment in perspective,- portions of the house being shown in dot and dash lines.

The channel carbon black plant includes a hot house 10, a plurality of burner pipes 12 extending horizontally almost the entire length of the hot house, which may be 140-200 ft. in length, and being equipped with a multiplicity of burner tips 14 through which the gas flames are fed. A channel member 16 is suspended over each longitudinal gas pipe 12. Air to support combustion of the gas flowing in separate jets from tips .14 enters the hot house beneath the side walls. Excess air and products of combustion pass out of the hot house through stack 18 and openings 20.

Carbon black is formed in these many gas flames to which insufiicient air for complete combustion is supplied and is deposited by impingement upon the under surface of the channels 16 from which it is removed, as the channels slowly reciprocate past scrapers (not shown) held against the depositing surface. The black scraped off falls into hoppers and thence into a screw-conveyor for ultimate recovery. The collection equipment referred to is not shown in the drawing as being standard equipment in the channel carbon black industry.

Gas is supplied to the hot house through supply pipe 22 provided with the usual valve 23 and orifice flange 24,

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connected into a gas main which supplies all of the other hot houses in a producing unit which may include 60 hot houses, more or less. From supply pipe 22 the gas is distributed, about midway of the hot house, through a cross-pipe 25, here shown as being of substantially larger diameter than that of the supply pipe but which may be of the same diameter, to a pair of parallel ground pipes 26 which extend the full length of the hot house. Risers 28 carry the gas to manifolds 30 through which the gas is distributed to longitudinal burner pipes 12. Each hot house may contain some three thousand burner tips 14 of lava or steatite, each tip supplying from approximately 45 to cubic feet of gas per 24 hour day. Gas flows for the entirehot building may range from 150,000 to as high as 260,000 cu. ft. of gas per 24 hr. day.

When burning natural gas alone in the channel process and with the aid of flame shields and air guiding devices within the hot house 10 the maximum yield of carbon black obtainable is about 2% lbs. per thousand cu. ft. of gas burned.

In the practice wecan use for enrichment any liquid hydrocarbon having a distillation end point of below about 950 R, which material is hereinafter referred to as the oil. Oil from a main supply pipe 32 is taken olf by a branch pipe34 and passed through filter 36. As this filter must be very fine the oil is preferably maintained under a pressure of between about 25 and 50 p.s.i.g. A pressure gauge 37 is provided for each hot house oil supply line. From the filter the oil is carried through a pipe 38 and through a very fine orifice, drilled in a blank secured within coupling 40, which largely controls the rates of oil flow. For flows from 1 to 5 gals. of oil per hour the orifice is of capillary size, being in the order of about 0.02 inch in diameter. Slightly larger orifices are used for higher rates of flow. The oil passing through this orifice then drips or flows in a very fine stream through pipe 42 into gas supply pipe 22 wherein it is vaporized in its passage to the burner tips. The oil may be delivered to supply pipe 22 at a point near the hot house inlet end as shown in the drawing or at any convenient downstream point. A draw-off cock 44 and shut off valve 45 are provided to permit cleaning out of the line when and if necessary.

It has been found that incremental yields from various cracked recycle and cracked distillate oils average about 2% lbs. of carbon black per gallon. From oils of higher aromacity somewhat higher yields are obtainable.

United States Patent No. 2,719,078, Billings and Dar- Wll'l, describes the apparatus herin shown up to this point. In order to introduce the required antioxidant to the oilgas-air mixture, a pipe 46 is connected to the oil pipe 38 as the latter leads away from the filter 36. In the pipe 46 is provided a valve 47 by which the flow of antioxidant may be regulated. For example, operating at flow rates of M c.f.d gas, 100 M c.f.d. air and 7 or 8 gallons oil per hour, the addition of 1% by weight of Catalin AC-1 antioxidant has permitted operation to continue without a break for 5 8 hours and at the end of that time the tips were still coke free. When operating the same equipment without the antioxidant almost all of the 3240 burner tips in the hot house had forks after 16 to 20 hours. Catalin antioxidant AC-l is 2,6-ditertiary-butylpara-cresol. It is readily obtainable in the market, is nontoxic and stable over long periods of storage. If obtained in crystalline form it is very highly soluble in such solvents as gasoline, toluene or alcohol. However, our invention is not restricted to this or to any specific antioxidant, nor to the introduction of the antioxidant at any specific point in the process so long as it arrives at the combustion zone. Satisfactory results have been obtained with other antioxidants having equivalent characteristics such, for example, as dicyclopentienyliron (ferrocene), certain haloalkyl thionophosphorous compounds, tricresyl phosphate, and organic boron compounds, as well as other alkyl-phenols, of which Catalin AC-l is only one example.

These and other suitable antioxidants will all be found to have a substantial vapor pressure at the temperature prevailing in the process, i.e. at 300 F. and above.

It will be understood that the antioxidant, Catalin AC-l, may be dissolved and premixed in the oil at any convenient point of the supply line.

Having thus disclosed our invention and described in detail of a typical manner of carrying it out, we claim as new and desire to secure by Letters Patent:

1. The process of producing impingement carbon black of high color, characterized by burning natural gas enriched with oil in a ratio of more than one (1) gallon of oil to 3750 cubic feet of gas diluted with air, flowing an antioxidant into the gas -oil-air mixture, conducting the resulting mixture through a heated distribution zone to burner outlets, thus vaporizing the resulting mixture, and recovering the carbon black thus produced without air oxidation of the oil in the air-diluted burning mixture.

2. The process described in claim 1 further characterized in that the operating flow rates are substantially as 4 follows: M c.f.d gas, 100 M c.f.d air, 7 to 8 gallons of oil per hour with the addition of approximately 1% of an alkyl phenol on the weight of oil.

3. A process for the production of channel carbon black which comprises flowing a liquid hydocarbon oil having a distillation end point below 950 F. with an admixture of an antioxidant directly into a stream of com- References Cited in the file of this patent UNITED STATES PATENTS 2,139,766 Mikeska et a1. Dec. 13, 1938 2,719,078 Billings et al. Sept. 27, 1955 FOREIGN PATENTS 500,467 Great Britain Feb. 9, 1939 695,841 Great Britain Aug. 19, 1953 

1. THE PROCESS OF PRODUCING IMPINGEMENT CARBON BLACK OF HIGH COLOR, CHARACTERIZED BY BURNING NATURAL GAS ENRICHED WITH OIL IN A RATIO OF MORE THAN ONE (1) GALLON OF OIL TO 3750 CUBIC FEET GAS DILUTED WITH AIR, FLOWING AN ANTIOXIDANT INTO THE GAS-OIL-AIR MIXTURE, CONDUCTING THE 